alsa_writer.c

   1 /*
   2  * Copyright (C) 2005-2006 Andre Noll <maan@systemlinux.org>
   3  *
   4  *     This program is free software; you can redistribute it and/or modify
   5  *     it under the terms of the GNU General Public License as published by
   6  *     the Free Software Foundation; either version 2 of the License, or
   7  *     (at your option) any later version.
   8  *
   9  *     This program is distributed in the hope that it will be useful,
  10  *     but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  *     GNU General Public License for more details.
  13  *
  14  *     You should have received a copy of the GNU General Public License
  15  *     along with this program; if not, write to the Free Software
  16  *     Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
  17  */
  18
  19 /** \file alsa_writer.c paraslash's alsa output plugin */
  20
  21 /*
  22  * Based in parts on aplay.c from the alsa-utils-1.0.8 package,
  23  * Copyright (c) by Jaroslav Kysela <perex@suse.cz>, which is
  24  * based on the vplay program by Michael Beck.
  25  */
  26
  27 #include "para.h"
  28 #include "fd.h"
  29 #include "string.h"
  30 #include "write.h"
  31
  32 #include <alsa/asoundlib.h>
  33
  34 #include "write.cmdline.h"
  35 #include "error.h"
  36
  37 extern struct gengetopt_args_info conf;
  38
  39 #define FORMAT SND_PCM_FORMAT_S16_LE
  40
  41 /** data specific to the alsa writer */
  42 struct private_alsa_data {
  43 /** the alsa handle */
  44 snd_pcm_t *handle;
  45 /** determined and set by alsa_open() */
  46 size_t bytes_per_frame;
  47 };
  48
  49 /*
  50  * open and prepare the PCM handle for writing
  51  *
  52  * Install PCM software and hardware configuration. Exit on errors.
  53  */
  54 static int alsa_open(struct writer_node *w)
  55 {
  56         snd_pcm_hw_params_t *hwparams;
  57         snd_pcm_sw_params_t *swparams;
  58         snd_pcm_uframes_t buffer_size, xfer_align, start_threshold,
  59                 stop_threshold;
  60         unsigned buffer_time = 0;
  61         int err;
  62         snd_pcm_info_t *info;
  63         snd_output_t *log;
  64         snd_pcm_uframes_t period_size;
  65         struct private_alsa_data *pad = para_malloc(sizeof(struct private_alsa_data));
  66         w->private_data = pad;
  67
  68         snd_pcm_info_alloca(&info);
  69         if (snd_output_stdio_attach(&log, stderr, 0) < 0)
  70                 return -E_ALSA_LOG;
  71         err = snd_pcm_open(&pad->handle, conf.device_arg,
  72                 SND_PCM_STREAM_PLAYBACK, 0);
  73         if (err < 0)
  74                 return -E_PCM_OPEN;
  75         if ((err = snd_pcm_info(pad->handle, info)) < 0)
  76                 return -E_SND_PCM_INFO;
  77
  78         snd_pcm_hw_params_alloca(&hwparams);
  79         snd_pcm_sw_params_alloca(&swparams);
  80         if (snd_pcm_hw_params_any(pad->handle, hwparams) < 0)
  81                 return -E_BROKEN_CONF;
  82         if (snd_pcm_hw_params_set_access(pad->handle, hwparams,
  83                         SND_PCM_ACCESS_RW_INTERLEAVED) < 0)
  84                 return -E_ACCESS_TYPE;
  85         if (snd_pcm_hw_params_set_format(pad->handle, hwparams, FORMAT) < 0)
  86                 return -E_SAMPLE_FORMAT;
  87         if (snd_pcm_hw_params_set_channels(pad->handle, hwparams,
  88                         conf.channels_arg) < 0)
  89                 return -E_CHANNEL_COUNT;
  90         if (snd_pcm_hw_params_set_rate_near(pad->handle, hwparams,
  91                         (unsigned int*) &conf.sample_rate_arg, 0) < 0)
  92                 return -E_SET_RATE;
  93         err = snd_pcm_hw_params_get_buffer_time_max(hwparams, &buffer_time, 0);
  94         if (err < 0 || !buffer_time)
  95                 return -E_GET_BUFFER_TIME;
  96         PARA_DEBUG_LOG("buffer time: %d\n", buffer_time);
  97         if (snd_pcm_hw_params_set_buffer_time_near(pad->handle, hwparams,
  98                         &buffer_time, 0) < 0)
  99                 return -E_SET_BUFFER_TIME;
 100         if (snd_pcm_hw_params(pad->handle, hwparams) < 0)
 101                 return -E_HW_PARAMS;
 102         snd_pcm_hw_params_get_period_size(hwparams, &period_size, 0);
 103         snd_pcm_hw_params_get_buffer_size(hwparams, &buffer_size);
 104         PARA_DEBUG_LOG("buffer size: %lu, period_size: %lu\n", buffer_size,
 105                 period_size);
 106         if (period_size == buffer_size)
 107                 return -E_BAD_PERIOD;
 108         snd_pcm_sw_params_current(pad->handle, swparams);
 109         err = snd_pcm_sw_params_get_xfer_align(swparams, &xfer_align);
 110         if (err < 0 || !xfer_align)
 111                 return -E_GET_XFER;
 112         snd_pcm_sw_params_set_avail_min(pad->handle, swparams, period_size);
 113         /* round to closest transfer boundary */
 114         start_threshold = (buffer_size / xfer_align) * xfer_align;
 115         if (start_threshold < 1)
 116                 start_threshold = 1;
 117         if (snd_pcm_sw_params_set_start_threshold(pad->handle, swparams,
 118                         start_threshold) < 0)
 119                 return -E_START_THRESHOLD;
 120         stop_threshold = buffer_size;
 121         if (snd_pcm_sw_params_set_stop_threshold(pad->handle, swparams,
 122                         stop_threshold) < 0)
 123                 return -E_STOP_THRESHOLD;
 124         if (snd_pcm_sw_params_set_xfer_align(pad->handle, swparams,
 125                         xfer_align) < 0)
 126                 return -E_SET_XFER;
 127         if (snd_pcm_sw_params(pad->handle, swparams) < 0)
 128                 return -E_SW_PARAMS;
 129         pad->bytes_per_frame = snd_pcm_format_physical_width(FORMAT)
 130                 * conf.channels_arg / 8;
 131         return period_size * pad->bytes_per_frame;
 132 }
 133
 134 /**
 135  * push out pcm frames
 136  * \param data pointer do data to be written
 137  * \param nbytes number of bytes (not frames)
 138  *
 139  * \return Number of bytes written, -E_ALSA_WRITE on errors.
 140  */
 141 static int alsa_write(char *data, size_t nbytes, struct writer_node *wn)
 142 {
 143         struct private_alsa_data *pad = wn->private_data;
 144         size_t frames = nbytes / pad->bytes_per_frame;
 145         unsigned char *d = (unsigned char*)data;
 146         snd_pcm_sframes_t r, result = 0;
 147
 148         while (frames > 0) {
 149                 /* write interleaved frames */
 150                 r = snd_pcm_writei(pad->handle, d, frames);
 151                 if (r < 0)
 152                         PARA_ERROR_LOG("write error: %s\n", snd_strerror(r));
 153                 if (r == -EAGAIN || (r >= 0 && r < frames))
 154                         snd_pcm_wait(pad->handle, 1);
 155                 else if (r == -EPIPE)
 156                         snd_pcm_prepare(pad->handle);
 157                 else if (r < 0)
 158                         return -E_ALSA_WRITE;
 159                 if (r > 0) {
 160                         result += r;
 161                         frames -= r;
 162                         d += r * pad->bytes_per_frame;
 163                 }
 164         }
 165         return result * pad->bytes_per_frame;
 166 }
 167
 168 static void alsa_close(struct writer_node *wn)
 169 {
 170         struct private_alsa_data *pad = wn->private_data;
 171         snd_pcm_drain(pad->handle);
 172         snd_pcm_close(pad->handle);
 173         snd_config_update_free_global();
 174         free(pad);
 175 }
 176
 177 /** the init function of the alsa writer */
 178 void alsa_writer_init(struct writer *w)
 179 {
 180         w->open = alsa_open;
 181         w->write = alsa_write;
 182         w->close = alsa_close;
 183         w->shutdown = NULL; /* nothing to do */
 184 }